Thanks for posting your query.
Prolonged weakness and depression suggest chronic fatigue syndrome
. Both conditions often overlap. Cause of both diseases is unknown but it can be due to previous infections. To diagnose it other diseases should be ruled out like liver diseases, thyroid disease
,adrenal disease,cancer etc.
If you have not got these labs then you may perform ESR, thyroid profile,LFT, CT scan and MRI.
You should also consult your psychiatrist
for further evaluation.
Hope it helps.